Fix YouTube's Alt-Tab Pause/Play Issue

FixYoutubeAltTabPlayPauseIssue.user.js

// ==UserScript==
// @name         Fix YouTube's Alt-Tab Pause/Play Issue
// @namespace    http://tampermonkey.net/
// @version      0.4
// @description  Fix YouTube's Alt-Tab Pause/Play Issue
// @author       HPZ07
// @match        https://www.youtube.com/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=youtube.com
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    window.addEventListener('keyup', keyHandler);
    window.addEventListener('keydown', keyDownHandler);
    const nonTriggerableElements = ['search', 'contenteditable-root', 'gsfi ytd-searchbox', 'ytd-searchbox', 'style-scope yt-formatted-string'];

    let video = document.querySelector('video');
    let videoState;

    function canTriggerSpaceAction() {
        return !nonTriggerableElements.some(element => {
            return document.activeElement.matches(`.${element}`) || document.activeElement.id === element;
        });
    }

    function keyHandler(e) {
        if (!canTriggerSpaceAction() || e.code !== 'Space' || !isWatchPage) return;
        video = document.querySelector('video');
        if (videoState === "play") video.play();;
        if (videoState === "pause") video.pause();
    }

    function keyDownHandler(e) {
        if(!isWatchPage) return;
        videoState = video.paused ? "play" : "pause";
        keyHandler(e);
    }

    function isWatchPage() {
        return /^\/watch/.test(location.pathname);
    }

})();

0.4 should fix the problem(hopefully). Using a wildcard character on YouTube (e.g., watch*) may not be ideal due to YouTube's asynchronous content loading.

function isWatchPage() {
     return /^\/watch/.test(location.pathname);
}

If you open a video in a new tab and the first thing you do is Alt+Tab, it won't register the first space but will after that.

The space bar doesn't work correctly on embedded videos. You should exclude them with this line:

// @exclude https://www.youtube.com/embed/*

Awesome script! Thanks @HPZ07 !

Big Thanks